1. Technical Field
Example embodiments of the present invention relate to a memory device and more specifically to a non-volatile memory device using a resistance change.
2. Related Art
Recently, while demand for portable digital devices such as digital cameras, MPEG-1 Audio Layer-3 (MP3) players, personal digital assistants (PDAs), and cellular phones is increased, the non-volatile memory market has expanded rapidly. A NAND flash memory is a representative programmable non-volatile memory device, and a resistive memory device (e.g., a resistive random-access memory (ReRAM)) using a variable resistor of which a resistance value is reversibly changed is being focused on as a non-volatile memory device that can replace the NAND flash memory.
Since the ReRAM uses a physical property, which is a resistance value of a variable resistor, as a state of data by itself, and can be driven with low power, a low-power memory device in which a cell configuration is simplified may be implemented. However, since a typical ReRAM is manufactured to have a metal-insulator-metal (MIM) laminated structure in which a metal, an insulating layer, and a metal are stacked, a high-temperature oxidation process is required to form the insulating layer. The high-temperature oxidation process makes application of polymer elements difficult because it is difficult to perform a high-temperature process using the polymer elements, and thus it is becoming a limiting factor for new applications such as a flexible device. As an alternative technique, a low-temperature process in which the insulating layer is formed using wet coating based on solution is being proposed. However, since it is difficult to obtain a reliable and uniform insulating layer by using such a wet process, the actual application of the non-volatile memory device is limited.